1. Field of the Invention
The present invention relates to an apparatus and method for recording and/or reproducing a digital signal, and more particularly to such an apparatus and method suitable for use in recording and/or reproducing a digital signal transferred from a computer or the like.
2. Description of the Prior Art
In practice, data stored in a hard disk or the like of a computer can be transferred to and recorded by a data streamer (data-recorder) once a day so as to protect the data or back up the same.
For this operation, or as a data recorder, analog audio tape recorders have been conventionally used in many cases. However, analog tape recorders have disadvantages in that they need an excessive amount of a recording medium or magnetic tape for recording and operate at a quite low data transferring rate upon recording, so that it takes too much time to transfer and record such data information. Moreover, analog tape recorders have problems, e.g. the starting point of a desired portion of the recorded data information cannot be rapidly searched for, and so on.
Thus, to overcome the above-mentioned problems, it is thought to utilize a helical-scan type DAT (digital audio tape recorder) using a rotary head, that is, a so-called recently commercialized DAT as a data recorder. Such data recorders utilizing a DAT are described in U.S. Pat. Nos. 4,873,589, 4,899,232, and 4,876,616 and in co-pending U.S. patent application Ser. No. 210,229 filed June 23, 1988. by one of the assignees of the present application.
To utilize the DAT as a data recorder, data transferred from a host computer is transformed in accordance with a DAT format before recording. In the DAT format, one frame is made up of two oblique tracks formed by one rotation of two heads having different azimuth angles. 16-bit PCM audio data, which has been interleaved, and auxiliary sub-data are recorded in this one frame area as a unit. During recording, there are formed in each track a main area for recording the PCM data and a sub-area for recording the sub-data.
The DAT has a high-speed search function. The high-speed search operation in the conventional DAT is performed by the method shown in FIG. 1.
In FIG. 1, when a target position of a magnetic tape 15 on which position signals "1", "2", "3", . . . are recorded is designated as, e.g., "4" in performing a search operation, a position detection signal is detected while driving the tape 15 at a 200-times normal playback speed. When the target position "4" is detected, a stop signal is supplied, and the tape 15 passes by the target position and is then stopped. The tape 15 then travels in the reverse direction at 16 times normal speed, and when the target position is detected, a stop signal is supplied. In this case, the tape 15 passes by the target position and is again stopped. The tape 15 is again reversed and travels at 3 times the normal speed. When the target position is detected, the stop signal is supplied. The tape 15 is again reversed and travels in the reverse direction at the normal speed. When the target position is detected and the stop signal is supplied, the tape 15 slightly passes by the target position, and is then stopped. In this case, a search end signal is output, and the next command signal is awaited. When the command signal is input in this waiting state, the magnetic tape 15 travels in the opposite direction at the normal speed, and the target position "4" is accurately detected.
The conventional high-speed search operation is performed as described above. Since the tape is kept stopped after the search end signal is output until the next command signal is input, there is a time loss, thus impairing the efficiency of the search operation.